Metal nitride material for thermistor, method for producing same, and film-type thermistor sensor

ABSTRACT

A metal nitride material for a thermistor consists of a metal nitride represented by the general formula: MxAly(N1-wOw)z (where “M” represents at least one of Fe, Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0&lt;w≤0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. A method for producing the metal nitride material for a thermistor includes a deposition step of performing film deposition by reactive sputtering in a nitrogen and oxygen-containing atmosphere using an M-Al alloy sputtering target (where “M” represents at least one of Fe, Co, Mn, Cu, and Ni).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending application: “METAL NITRIDEMATERIAL FOR THERMISTOR, METHOD FOR PRODUCING SAME, AND FILM-TYPETHERMISTOR SENSOR” filed even date herewith in the names of ToshiakiFUJITA, Hiroshi TANAKA and Noriaki NAGATOMO as a national phase entry ofPCT/JP2014/070286 filed Jul. 24, 2014, which application is assigned tothe assignee of the present application and is incorporated by referenceherein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a metal nitride material for athermistor, which can be directly deposited on a film or the likewithout firing, a method for producing the same, and a film-typethermistor sensor.

Description of the Related Art

There is a demand for a thermistor material used for a temperaturesensor or the like having a high B constant in order to obtain a highprecision and high sensitivity thermistor sensor. Conventionally,transition metal oxides of Mn, Co, Fe, and the like are typically usedas such thermistor materials (see Patent Documents 1 to 3). Thesethermistor materials need a heat treatment such as firing at atemperature of 550° C. or higher in order to obtain a stable thermistorcharacteristic/property.

In addition to thermistor materials consisting of metal oxides asdescribed above, Patent Document 4 discloses a thermistor materialconsisting of a nitride represented by the general formula:M_(x)A_(y)N_(z) (where “M” represents at least one of Ta, Nb, Cr, Ti,and Zr, “A” represents at least one of Al, Si, and B, 0.1≤x≤0.8,0<y≤0.6, 0.1≤z≤0.8, and x+y+z=1). In Patent Document 4, only aTa—Al—N-based material consisting of a nitride represented by thegeneral formula: M_(x)A_(y)N_(z) (where 0.5≤x≤0.8, 0.1≤y≤0.5, 0.2≤z≤0.7,and x+y+z=1) is described in an Example. The Ta—Al—N-based material isproduced by sputtering in a nitrogen gas-containing atmosphere using amaterial containing the element(s) listed above as a target. Theresultant thin film is subject to a heat treatment at a temperature from350 to 600° C. as required.

Other than thermistor materials, Patent document 5 discloses aresistance film material for a strain sensor, which consists of anitride represented by the general formula: Cr_(100-x-y)N_(x)M_(y)(where “M” is one or more elements selected from Ti, V, Nb, Ta, Ni, Zr,Hf, Si, Ge, C, O, P, Se, Te, Zn, Cu, Bi, Fe, Mo, W, As, Sn, Sb, Pb, B,Ga, In, Tl, Ru, Rh, Re, Os, Ir, Pt, Pd, Ag, Au, Co, Be, Mg, Ca, Sr, Ba,Mn, Al, and rare earth elements, the crystal structure thereof iscomposed of mainly a bcc structure or mainly a mixed structure of a bccstructure and A15 type structure, 0.0001≤x≤30, 0≤y≤30, and0.0001≤x+y≤50). The resistance film material for a strain sensor isemployed for measuring strain and stress from changes in the resistanceof the sensor made of a Cr—N-based strain resistance film, where both ofthe amounts of nitrogen (x) and an accessory component element(s) M (y)are 30 at % or lower, as well as for performing various conversions. TheCr—N-M-based material is produced by reactive sputtering in a depositionatmosphere containing the accessory gaseous element(s) using a materialcontaining the above-described element(s) or the like as a target. Theresultant thin film is subject to a heat treatment at a temperature from200 to 1000° C. as required.

PRIOR ART DOCUMENTS Patent Documents

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2000-068110

[Patent Document 2] Japanese Unexamined Patent Application PublicationNo. 2000-348903

[Patent Document 3] Japanese Unexamined Patent Application PublicationNo. 2006-324520

[Patent Document 4] Japanese Unexamined Patent Application PublicationNo. 2004-319737

[Patent Document 5] Japanese Unexamined Patent Application PublicationNo. H10-270201

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The following problems still remain in the conventional techniquesdescribed above.

In recent years, the development of a film-type thermistor sensor madeof a thermistor material formed on a resin film has been considered, andthus, it has been desired to develop a thermistor material that can bedirectly deposited on a film. Specifically, it is expected that aflexible thermistor sensor will be obtained by using a film.Furthermore, it is desired to develop a very thin thermistor sensorhaving a thickness of about 0.1 mm. Although a substrate materialincluding a ceramic such as alumina has often been conventionally used,there is a problem that if this substrate material is thinned to athickness of 0.1 mm for example, it is very fragile and breaks easily.Therefore, it is expected that a very thin thermistor sensor will beobtained by using a film.

However, a film made of a resin material typically has a low heatresistance temperature of 150° C. or lower, and even polyimide, which isknown as a material having a relatively high heat resistancetemperature, only has a heat resistance temperature of about 200° C.Hence, when a heat treatment is performed in a process of forming athermistor material, it has been conventionally difficult to apply sucha resin material. Since the above-described conventional oxidethermistor material needs to be fired at a temperature of 550° C. orhigher in order to realize a desired thermistor characteristic, afilm-type thermistor sensor in which the thermistor material is directlydeposited on a film cannot be realized. Therefore, it has been desiredto develop a thermistor material that can be directly deposited on afilm without firing. However, even the thermistor material disclosed inPatent Document 4 still needs a heat treatment on the resultant thinfilm at a temperature from 350 to 600° C. as required in order to obtaina desired thermistor characteristic. Regarding this thermistor material,a B constant of about 500 to 3000 K was obtained in an Example of theTa—Al—N-based material, but the heat resistance of this material is notdescribed and therefore, the thermal reliability of a nitride-basedmaterial is unknown.

In addition, since the Cr—N-M-based material disclosed in Patentdocument 5 has a low B constant of 500 or lower and cannot ensure heatresistance to a temperature of 200° C. or lower unless a heat treatmentin the range of 200° C. to 1000° C. is performed, a film-type thermistorsensor in which the thermistor material is directly deposited on a filmcannot be realized. Therefore, it has been desired to develop athermistor material that can be directly deposited on a film withoutfiring.

The present invention has been made in view of the aforementionedcircumstances, and an object of the present invention is to provide ametal nitride material for a thermistor, which has a high heatresistance and a high reliability and can be directly deposited on afilm or the like without firing, a method for producing the same, and afilm-type thermistor sensor.

Means for Solving the Problems

The present inventors' serious endeavor carried out by focusing on anAl—N-based material among nitride materials found that the Al—N-basedmaterial having a good B constant and an excellent heat resistance maybe obtained without firing by substituting the Al site with a specificmetal element for improving electric conductivity and by forming it intoa specific crystal structure even though Al—N is an insulator anddifficult to provide with an optimum thermistor characteristic (Bconstant: about 1000 to 6000 K).

Therefore, the present invention has been made on the basis of the abovefinding, and adopts the following configuration in order to overcome theaforementioned problems.

Specifically, a metal nitride material for a thermistor according to afirst aspect of the present invention is characterized by a metalnitride material used for a thermistor, which consists of a metalnitride represented by the general formula:M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where “M” represents at least one of Fe,Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<w≤0.35, andx+y+z=1), wherein the crystal structure thereof is a hexagonalwurtzite-type single phase.

Therefore, in the case where “M” is Fe, the general formula isFe_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1). In the case where “M” is Co, the general formulais Co_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1). In the case where “M” is Mn, the general formulais Mn_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1). In the case where “M” is Cu, the general formulais Cu_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1). In the case where “M” is Ni, the general formulais Ni_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1).

Since this metal nitride material for a thermistor consists of a metalnitride represented by the general formula:M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where “M” represents at least one of Fe,Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<w≤0.35, andx+y+z=1), wherein the crystal structure thereof is a hexagonalwurtzite-type single phase, a good B constant and a high heat resistancecan be obtained without firing. In particular, the heat resistance canbe further improved by the effect of oxygen (0) included in a crystal soas to compensate nitrogen defects in the crystal or to introduceinterstitial oxygen therein, or the like.

Note that, when the value of “y/(x+y)” (i.e., Al/(M+Al)) is less than0.70, a wurtzite-type single phase cannot be obtained, but twocoexisting crystal phases of a wurtzite-type phase and a NaCl-type phaseor a crystal phase of only a NaCl-type phase may be obtained, so that asufficiently high resistance and B constant cannot be obtained.

When the value of “y/(x+y)” (i.e., Al/(M+Al)) exceeds 0.98, the metalnitride material exhibits very high resistivity and extremely highelectrical insulation, so that the metal nitride material is notapplicable as a thermistor material.

When the value of “z” (i.e., (N+O)/(M+Al+N+O)) is less than 0.45, thenitridation amount is too small to obtain a wurtzite-type single phase.Consequently, a sufficiently high resistance and B constant cannot beobtained.

In addition, when the value of “z” (i.e., (N+O)/(M+Al+N+O)) exceeds0.55, a wurtzite-type single phase cannot be obtained. This is becausethe stoichiometric ratio in the absence of defects at the nitrogen sitein a wurtzite-type single phase is 0.5 (i.e., N/(M+Al+N)=0.5), andbecause the stoichiometric ratio when all defects at the nitrogen siteare compensated by oxygen is 0.5 (i.e., (N+O)/(M+Al+N+O)=0.5). Theamount of “z” exceeding 0.5 may be due to the interstitial oxygenintroduced in a crystal or due to the quantitative accuracy of the lightelements (nitrogen, oxygen) in an XPS analysis.

Further, in this study, when the value of “w” (i.e., O/(N+O)) exceeds0.35, a wurtzite-type single phase cannot be obtained. The reason willbe understandable considering the fact that, in the case where w=1 andy/(x+y)=0, a corundum-type Fe₂O₃ phase is formed (where “M” is Fe), aspinel-type Co₃O₄ phase is formed (where “M” is Co), a spinel-type Mn₃O₄phase is formed (where “M” is Mn), a tenorite-type CuO phase is formed(where “M” is Cu), and a NaCl-type Nio phase (insulator) is formed(where “M” is Ni), whereas, in the case where w=1 and y/(x+y)=1, acorundum-type Al₂O₃ phase is formed. It has been found in this studythat when the value of “w” increases, that is, the amount of oxygenincreases with respect to the amount of nitrogen, it is difficult toobtain a wurtzite-type single phase, and hence, a wurtzite-type singlephase can be obtained only when O/(N+O) is 0.35 or less.

A metal nitride material for a thermistor according to a second aspectof the present invention is characterized in that the metal nitridematerial for a thermistor according to the first aspect of the presentinvention is deposited as a film, and is a columnar crystal extending ina vertical direction with respect to the surface of the film.

Specifically, since this metal nitride material for a thermistor is acolumnar crystal extending in a vertical direction with respect to thesurface of the film, the crystallinity of the film is high, so that ahigh heat resistance can be obtained.

A film-type thermistor sensor according to a third aspect of the presentinvention is characterized by including an insulating film; a thin filmthermistor portion made of the metal nitride material for a thermistoraccording to the first or second aspect of the present invention formedon the insulating film; and a pair of pattern electrodes formed at leaston the top or the bottom of the thin film thermistor portion.

Specifically, since the thin film thermistor portion made of the metalnitride material for a thermistor according to the first or secondaspect of the present invention is formed on the insulating film in thisfilm-type thermistor sensor, an insulating film having a low heatresistance such as a resin film can be used because the thin filmthermistor portion is formed without firing and has a high B constantand a high heat resistance, so that a thin and flexible thermistorsensor having an excellent thermistor characteristic can be obtained.

A substrate material including a ceramic such as alumina that has oftenbeen conventionally used has the problem that if this substrate materialis thinned to a thickness of 0.1 mm for example, it is very fragile andbreaks easily. On the other hand, since a film can be used in thepresent invention, a very thin film-type thermistor sensor having athickness of 0.1 mm, for example, can be obtained.

A method for producing a metal nitride material for a thermistoraccording to a fourth aspect of the present invention is characterizedin that the method for producing the metal nitride material for athermistor according to the first or second aspect of the presentinvention includes a deposition step of performing film deposition byreactive sputtering in a nitrogen and oxygen-containing atmosphere usingan M-Al alloy sputtering target (where “M” represents at least one ofFe, Co, Mn, Cu, and Ni).

Specifically, since the film deposition is performed by reactivesputtering in a nitrogen and oxygen-containing atmosphere using an M-Alalloy sputtering target (where “M” represents at least one of Fe, Co,Mn, Cu, and Ni) in this method for producing the metal nitride materialfor a thermistor, the metal nitride material for a thermistor of thepresent invention, which consists of the aforementionedM_(x)Al_(y)(N,O)_(z), can be deposited on a film without firing.

Effects of the Invention

According to the present invention, the following effects may beprovided.

Specifically, since the metal nitride material for a thermistoraccording to the present invention consists of a metal nitriderepresented by the general formula: M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where“M” represents at least one of Fe, Co, Mn, Cu, and Ni,0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1), wherein thecrystal structure thereof is a hexagonal wurtzite-type single phase, themetal nitride material having a good B constant and a high heatresistance can be obtained without firing. Also, since film depositionis performed by reactive sputtering in a nitrogen and oxygen-containingatmosphere using an M-Al alloy sputtering target (where “M” representsat least one of Fe, Co, Mn, Cu, and Ni) in the method for producing themetal nitride material for a thermistor according to the presentinvention, the metal nitride material for a thermistor of the presentinvention, which consists of M_(x)Al_(y)(N,O)_(z) described above, canbe deposited on a film without firing. Further, since a thin filmthermistor portion made of the metal nitride material for a thermistoraccording to the present invention is formed on an insulating film inthe film-type thermistor sensor according to the present invention, athin and flexible thermistor sensor having an excellent thermistorcharacteristic can be obtained by using an insulating film such as aresin film having a low heat resistance. Furthermore, since thesubstrate material is a resin film rather than a ceramic that becomesvery fragile and breaks easily when being thinned, a very thin film-typethermistor sensor having a thickness of 0.1 mm can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a Fe—Al—(N+O)-based ternary phase diagram illustrating thecomposition range of a metal nitride material for a thermistor accordingto one embodiment of a metal nitride material for a thermistor, a methodfor producing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 2 is a Co—Al—(N+O)-based ternary phase diagram illustrating thecomposition range of a metal nitride material for a thermistor accordingto one embodiment of a metal nitride material for a thermistor, a methodfor producing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 3 is a Mn—Al—(N+O)-based ternary phase diagram illustrating thecomposition range of a metal nitride material for a thermistor accordingto one embodiment of a metal nitride material for a thermistor, a methodfor producing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 4 is a Cu—Al—(N+O)-based ternary phase diagram illustrating thecomposition range of a metal nitride material for a thermistor accordingto one embodiment of a metal nitride material for a thermistor, a methodfor producing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 5 is a Ni—Al—(N+O)-based ternary phase diagram illustrating thecomposition range of a metal nitride material for a thermistor accordingto one embodiment of a metal nitride material for a thermistor, a methodfor producing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 6 is a perspective view illustrating a film-type thermistor sensoraccording to the present embodiment.

FIG. 7 is a perspective view illustrating a method for producing afilm-type thermistor sensor in the order of the steps according to thepresent embodiment.

FIG. 8 shows a front view and a plan view illustrating a film evaluationelement of a metal nitride material for a thermistor according to anExample of a metal nitride material for a thermistor, a method forproducing the same, and a film-type thermistor sensor of the presentinvention.

FIG. 9 is a graph illustrating the relationship between a resistivity at25° C. and a B constant according to Examples and Comparative Examplesof the present invention where “M” is Fe.

FIG. 10 is a graph illustrating the relationship between a resistivityat 25° C. and a B constant according to Examples and Comparative Exampleof the present invention where “M” is Co.

FIG. 11 is a graph illustrating the relationship between a resistivityat 25° C. and a B constant according to Examples and Comparative Exampleof the present invention where “M” is Mn.

FIG. 12 is a graph illustrating the relationship between a resistivityat 25° C. and a B constant according to Examples and Comparative Exampleof the present invention where “M” is Cu.

FIG. 13 is a graph illustrating the relationship between a resistivityat 25° C. and a B constant according to Examples and Comparative Exampleof the present invention where “M” is Ni.

FIG. 14 is a graph illustrating the relationship between an Al/(Fe+Al)ratio and a B constant according to Examples and Comparative Examples ofthe present invention.

FIG. 15 is a graph illustrating the relationship between an Al/(Co+Al)ratio and a B constant according to Examples and Comparative Example ofthe present invention.

FIG. 16 is a graph illustrating the relationship between an Al/(Mn+Al)ratio and a B constant according to Examples and Comparative Example ofthe present invention.

FIG. 17 is a graph illustrating the relationship between an Al/(Cu+Al)ratio and a B constant according to Examples and Comparative Example ofthe present invention.

FIG. 18 is a graph illustrating the relationship between an Al/(Ni+Al)ratio and a B constant according to Examples and Comparative Example ofthe present invention.

FIG. 19 is a graph illustrating the result of X-ray diffraction (XRD) inthe case of a strong c-axis orientation according to the Example of thepresent invention where Al/(Fe+Al)=0.92.

FIG. 20 is a graph illustrating the result of X-ray diffraction (XRD) inthe case of a strong c-axis orientation according to the Example of thepresent invention where Al/(Co+Al)=0.89.

FIG. 21 is a graph illustrating the result of X-ray diffraction (XRD) inthe case of a strong c-axis orientation according to the Example of thepresent invention where Al/(Mn+Al)=0.95.

FIG. 22 is a graph illustrating the result of X-ray diffraction (XRD) inthe case of a strong c-axis orientation according to the Example of thepresent invention where Al/(Cu+Al)=0.89.

FIG. 23 is a graph illustrating the result of X-ray diffraction (XRD) inthe case of a strong c-axis orientation according to the Example of thepresent invention where Al/(Ni+Al)=0.75.

FIG. 24 is a graph illustrating the relationship between an N/(Fe+Al+N)ratio and an O/(N+O) ratio.

FIG. 25 is a graph illustrating the relationship between an N/(Co+Al+N)ratio and an O/(N+O) ratio.

FIG. 26 is a graph illustrating the relationship between an N/(Mn+Al+N)ratio and an O/(N+O) ratio.

FIG. 27 is a graph illustrating the relationship between an N/(Cu+Al+N)ratio and an O/(N+O) ratio.

FIG. 28 is a graph illustrating the relationship between an N/(Ni+Al+N)ratio and an O/(N+O) ratio.

FIG. 29 is a cross-sectional SEM photograph illustrating a materialaccording to an Example of the present invention where “M” is Fe.

FIG. 30 is a cross-sectional SEM photograph illustrating a materialaccording to an Example of the present invention where “M” is Co.

FIG. 31 is a cross-sectional SEM photograph illustrating a materialaccording to an Example of the present invention where “M” is Mn.

FIG. 32 is a cross-sectional SEM photograph illustrating a materialaccording to an Example of the present invention where “M” is Cu.

FIG. 33 is a cross-sectional SEM photograph illustrating a materialaccording to an Example of the present invention where “M” is Ni.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a description will be given of a metal nitride material fora thermistor, a method for producing the same, and a film-typethermistor sensor according to one embodiment of the present inventionwith reference to FIGS. 1 to 7. In the drawings used in the followingdescription, the scale of each component is changed as appropriate sothat each component is recognizable or is readily recognized.

The metal nitride material for a thermistor of the present embodiment isa metal nitride material used for a thermistor, which consists of ametal nitride represented by the general formula:M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where “M” represents at least one of Fe,Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<w≤0.35, andx+y+z=1), wherein the crystal structure thereof is a hexagonalwurtzite-type (space group: P6₃mc (No. 186)) single phase.

For example, in the case where “M” is Fe, the metal nitride material fora thermistor of the present embodiment is a metal nitride material usedfor a thermistor, which consists of a metal nitride represented by thegeneral formula: Fe_(x)Al_(y)(N_(1-w)O_(w))_(z) (where0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<W≤0.35, and x+y+z=1), wherein thecrystal structure thereof is a hexagonal wurtzite-type (space group:P6₃mc (No. 186)) single phase. Specifically, this metal nitride materialfor a thermistor consists of a metal nitride having a composition withinthe region enclosed by the points A, B, C, and D in theFe—Al—(N+O)-based ternary phase diagram as shown in FIG. 1, wherein thecrystal phase thereof is a wurtzite-type.

In the case where “M” is Co, the metal nitride material for a thermistorof the present embodiment is a metal nitride material used for athermistor, which consists of a metal nitride represented by the generalformula: Co_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98,0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1), wherein the crystal structurethereof is a hexagonal wurtzite-type (space group: P6₃mc (No. 186))single phase. Specifically, this metal nitride material for a thermistorconsists of a metal nitride having a composition within the regionenclosed by the points A, B, C, and D in the Co—Al—(N+O)-based ternaryphase diagram as shown in FIG. 2, wherein the crystal phase thereof is awurtzite-type.

In the case where “M” is Mn, the metal nitride material for a thermistorof the present embodiment is a metal nitride material used for athermistor, which consists of a metal nitride represented by the generalformula: Mn_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98,0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1), wherein the crystal structurethereof is a hexagonal wurtzite-type (space group: P6₃mc (No. 186))single phase. Specifically, this metal nitride material for a thermistorconsists of a metal nitride having a composition within the regionenclosed by the points A, B, C, and D in the Mn—Al—(N+O)-based ternaryphase diagram as shown in FIG. 3, wherein the crystal phase thereof is awurtzite-type.

In the case where “M” is Cu, the metal nitride material for a thermistorof the present embodiment is a metal nitride material used for athermistor, which consists of a metal nitride represented by the generalformula: Cu_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98,0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1), wherein the crystal structurethereof is a hexagonal wurtzite-type (space group: P6₃mc (No. 186))single phase. Specifically, this metal nitride material for a thermistorconsists of a metal nitride having a composition within the regionenclosed by the points A, B, C, and D in the Cu—Al—(N+O)-based ternaryphase diagram as shown in FIG. 4, wherein the crystal phase thereof is awurtzite-type.

In the case where “M” is Ni, the metal nitride material for a thermistorof the present embodiment is a metal nitride material used for athermistor, which consists of a metal nitride represented by the generalformula: Ni_(x)Al_(y)(N_(1-w)O_(w))_(z) (where 0.70≤y/(x+y)≤0.98,0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1), wherein the crystal structurethereof is a hexagonal wurtzite-type (space group: P6₃mc (No. 186))single phase. Specifically, this metal nitride material for a thermistorconsists of a metal nitride having a composition within the regionenclosed by the points A, B, C, and D in the Ni—Al—(N+O)-based ternaryphase diagram as shown in FIG. 5, wherein the crystal phase thereof is awurtzite-type.

Note that the composition ratios of (x, y, z) (at o) at the points A, B,C, and D are A (x, y, z=13.5, 31.5, 55.0), B (x, y, z=0.9, 44.1, 55.0),C (x, y, z=1.1, 53.9, 45.0), and D (x, y, z=16.5, 38.5, 45.0),respectively.

Also, this metal nitride material for a thermistor is deposited as afilm, and is a columnar crystal extending in a vertical direction withrespect to the surface of the film. Furthermore, the metal nitridematerial for a thermistor is more strongly oriented along the c-axisthan the a-axis in a vertical direction with respect to the surface ofthe film.

The decision about whether a metal nitride material for a thermistor hasa strong a-axis orientation (100) or a strong c-axis orientation (002)in a vertical direction (film thickness direction) with respect to thesurface of the film is made by examining the orientation of the crystalaxis using X-ray diffraction (XRD). When the peak intensity ratio of(100)/(002), where (100) is the hkl index indicating a-axis orientationand (002) is the hkl index indicating c-axis orientation, is less than1, the metal nitride material for a thermistor is determined to have astrong c-axis orientation.

Next, a description will be given of a film-type thermistor sensor usingthe metal nitride material for a thermistor of the present embodiment.As shown in FIG. 6, a film-type thermistor sensor 1 includes aninsulating film 2, a thin film thermistor portion 3 made of the metalnitride material for a thermistor described above formed on theinsulating film 2, and a pair of pattern electrodes 4 formed at least onthe top of the thin film thermistor portion 3.

The insulating film 2 is, for example, a polyimide resin sheet formed ina band shape. The insulating film 2 may be made of another material suchas polyethylene terephthalate (PET), polyethylene naphthalate (PEN), orthe like.

The pair of pattern electrodes 4 has a pair of comb shaped electrodeportions 4 a that is patterned so as to have a comb shaped pattern byusing stacked metal films of, for example, a Cr film and an Au film andis arranged opposite to each other on the thin film thermistor portion3, and a pair of linear extending portions 4 b extending with the tipends thereof being connected to these comb shaped electrode portions 4 aand the base ends thereof being arranged at the end of the insulatingfilm 2.

A plating portion 4 c such as Au plating is formed as a lead wiredrawing portion on the base end of each of the pair of linear extendingportions 4 b. One end of the lead wire is joined with the platingportion 4 c via a solder material or the like. Furthermore, except forthe end of the insulating film 2 including the plating portions 4 c, apolyimide coverlay film 5 is pressure bonded onto the insulating film 2.Instead of the polyimide coverlay film 5, a polyimide or epoxy-basedresin material layer may be formed onto the insulating film 2 byprinting.

A description will be given below of a method for producing the metalnitride material for a thermistor and a method for producing thefilm-type thermistor sensor 1 using the metal nitride material for athermistor with reference to FIG. 7.

The method for producing the metal nitride material for a thermistoraccording to the present embodiment includes a deposition step ofperforming film deposition by reactive sputtering in a nitrogen andoxygen-containing atmosphere using an M-Al alloy sputtering target(where “M” represents at least one of Fe, Co, Mn, Cu, and Ni).

For example, in the case where “M” is Fe, a Fe—Al alloy sputteringtarget is used. In the case where “M” is Co, a Co—Al alloy sputteringtarget is used. In the case where “M” is Mn, a Mn—Al alloy sputteringtarget is used. In the case where “M” is Cu, a Cu—Al alloy sputteringtarget is used. In the case where “M” is Ni, a Ni—Al alloy sputteringtarget is used.

The sputtering gas pressure during the reactive sputtering describedabove is set to less than 1.5 Pa.

Furthermore, it is preferable that the deposited film is irradiated withnitrogen plasma after the deposition step.

More specifically, the thin film thermistor portion 3 having a thicknessof 200 nm, which is made of the metal nitride material for a thermistorof the present embodiment, is deposited on the insulating film 2 whichis, for example, a polyimide film having a thickness of 50 μm shown inFIG. 7(a) by the reactive sputtering method, as shown in FIG. 7(b).

In the case where “M” is Fe, the exemplary sputtering conditions are asfollows: an ultimate vacuum: 5×10⁻⁶ Pa, a sputtering gas pressure: 0.67Pa, a target input power (output): 300 W, and a nitrogen gas partialpressure and an oxygen gas partial pressure under a mixed gas (Argas+nitrogen gas+oxygen gas) atmosphere: 79.8% and 0.2%, respectively.

In the case where “M” is Co, the exemplary sputtering conditions are asfollows: an ultimate vacuum: 5×10⁻⁶ Pa, a sputtering gas pressure: 0.67Pa, a target input power (output): 300 W, and a nitrogen gas partialpressure and an oxygen gas partial pressure under a mixed gas (Argas+nitrogen gas+oxygen gas) atmosphere: 39.8% and 0.2%, respectively.

In the case where “M” is Mn, the exemplary sputtering conditions are asfollows: an ultimate vacuum: 5×10⁻⁶ Pa, a sputtering gas pressure: 0.4Pa, a target input power (output): 300 W, and a nitrogen gas partialpressure and an oxygen gas partial pressure under a mixed gas (Argas+nitrogen gas+oxygen gas) atmosphere: 59.8% and 0.2%, respectively.

In the case where “M” is Cu, the exemplary sputtering conditions are asfollows: an ultimate vacuum: 5×10⁻⁶ Pa, a sputtering gas pressure: 0.4Pa, a target input power (output): 300 W, and a nitrogen gas partialpressure and an oxygen gas partial pressure under a mixed gas (Argas+nitrogen gas+oxygen gas) atmosphere: 19.8% and 0.2%, respectively.

In the case where “M” is Ni, the exemplary sputtering conditions are asfollows: an ultimate vacuum: 5×10⁻⁶ Pa, a sputtering gas pressure: 0.4Pa, a target input power (output): 300 W, and a nitrogen gas partialpressure and an oxygen gas partial pressure under a mixed gas (Argas+nitrogen gas+oxygen gas) atmosphere: 29.8% and 0.2%, respectively.

In addition, the metal nitride material for a thermistor having adesired size is deposited on the insulating film 2 using a metal mask soas to form the thin film thermistor portion 3. It is preferable that theformed thin film thermistor portion 3 is irradiated with nitrogenplasma. For example, the thin film thermistor portion 3 is irradiatedwith nitrogen plasma under the degree of vacuum of 6.7 Pa, the output of200 W, and the N₂ gas atmosphere.

Next, a Cr film having a thickness of 20 nm is formed and an Au filmhaving a thickness of 200 nm is further formed thereon by the sputteringmethod, for example. Furthermore, patterning is performed as follows:after a resist solution has been coated on the stacked metal films usinga barcoater, pre-baking is performed for 1.5 minutes at a temperature of110° C.; after the exposure by an exposure device, any unnecessaryportions are removed by a developing solution, and then post-baking isperformed for 5 minutes at a temperature of 150° C. Then, anyunnecessary electrode portions are subject to wet etching usingcommercially available Au etchant and Cr etchant, and then the resist isstripped so as to form the pair of pattern electrodes 4 each having adesired comb shaped electrode portion 4 a as shown in FIG. 7(c). Notethat the pair of pattern electrodes 4 may be formed in advance on theinsulating film 2, and then the thin film thermistor portion 3 may bedeposited on the comb shaped electrode portions 4 a. In this case, thecomb shaped electrode portions 4 a of the pair of pattern electrodes 4are formed on the bottom of the thin film thermistor portion 3.

Next, as shown in FIG. 7(d), the polyimide coverlay film 5 with anadhesive having a thickness of 50 μm, for example, is placed on theinsulating film 2, and then they are bonded to each other underpressurization of 2 MPa at a temperature of 150° C. for 10 minutes usinga press machine. Furthermore, as shown in FIG. 7(e), an Au thin filmhaving a thickness of 2 μm is formed at the base ends of the linearextending portions 4 b using, for example, an Au plating solution so asto form the plating portions 4 c.

When a plurality of film-type thermistor sensors 1 is simultaneouslyproduced, a plurality of thin film thermistor portions 3 and a pluralityof pattern electrodes 4 are formed on a large-format sheet of theinsulating film 2 as described above, and then, the resultinglarge-format sheet is cut into a plurality of segments so as to obtain aplurality of film-type thermistor sensors 1.

In this manner, a thin film-type thermistor sensor 1 having a size of25×3.6 mm and a thickness of 0.1 mm, for example, is obtained.

As described above, since the metal nitride material for a thermistor ofthe present embodiment consists of a metal nitride represented by thegeneral formula: M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where “M” represents atleast one of Fe, Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1), wherein the crystal structure thereof is ahexagonal wurtzite-type (space group: P6₃mc (No. 186)) single phase, agood B constant and a high heat resistance can be obtained withoutfiring. In particular, the heat resistance can be further improved bythe effect of oxygen (O) included in a crystal so as to compensatenitrogen defects in the crystal or the like.

Also, since this metal nitride material for a thermistor is a columnarcrystal extending in a vertical direction with respect to the surface ofthe film, the crystallinity of the film is high, so that a high heatresistance can be obtained.

Since film deposition is performed by reactive sputtering in a nitrogenand oxygen-containing atmosphere using an M-Al alloy sputtering target(where “M” represents at least one of Fe, Co, Mn, Cu, and Ni) in themethod for producing the metal nitride material for a thermistor of thepresent embodiment, the metal nitride material for a thermistor, whichconsists of M_(x)Al_(y)(N,O)_(z) described above, can be deposited on afilm without firing.

Thus, since the thin film thermistor portion 3 made of the metal nitridematerial for a thermistor described above is formed on the insulatingfilm 2 in the film-type thermistor sensor 1 using the metal nitridematerial for a thermistor of the present embodiment, the insulating film2 having a low heat resistance, such as a resin film, can be usedbecause the thin film thermistor portion 3 is formed without firing andhas a high B constant and a high heat resistance, so that a thin andflexible thermistor sensor having an excellent thermistor characteristiccan be obtained.

A substrate material including a ceramic such as alumina that has oftenbeen conventionally used has the problem that if this substrate materialis thinned to a thickness of 0.1 mm, for example, it is very fragile andbreaks easily. On the other hand, since a film can be used in thepresent embodiment, a very thin film-type thermistor sensor having athickness of 0.1 mm, for example, can be provided.

EXAMPLES

Next, the evaluation results of the materials according to Examplesproduced based on the above embodiment regarding the metal nitridematerial for a thermistor, the method for producing the same, and thefilm-type thermistor sensor according to the present invention will bespecifically described with reference to FIGS. 8 to 33.

<Production of Film Evaluation Element>

The film evaluation elements 121 shown in FIG. 8 were produced accordingto Examples and Comparative Examples of the present invention asfollows.

Firstly, each of the thin film thermistor portions 3 having a thicknessof 500 nm which were made of the metal nitride materials for athermistor with the various composition ratios shown in Tables 1 to 5was formed on a Si wafer with a thermal oxidation film as a Si substrate(S) by using Fe—Al, Co—Al, Mn—Al, Cu—Al, and Ni—Al alloy targets withvarious composition ratios by the reactive sputtering method. The thinfilm thermistor portions 3 were formed under the sputtering conditionsof an ultimate degree of vacuum of 5×10⁻⁶ Pa, a sputtering gas pressureof from 0.1 to 1.5 Pa, a target input power (output) of from 100 to 500W, and a nitrogen gas partial pressure and an oxygen gas partialpressure under a mixed gas (Ar gas+nitrogen gas+oxygen gas) atmosphereof from 10 to 100% and from 0 to 3%, respectively.

Next, a Cr film having a thickness of 20 nm was formed and an Au filmhaving a thickness of 200 nm was further formed on each of the thin filmthermistor portions 3 by the sputtering method. Furthermore, patterningwas performed as follows: after a resist solution had been coated on thestacked metal films using a spin coater, pre-baking was performed for1.5 minutes at a temperature of 110° C.; after the exposure by anexposure device, any unnecessary portions were removed by a developingsolution, and then post-baking was performed for 5 minutes at atemperature of 150° C. Then, any unnecessary electrode portions weresubject to wet etching using commercially available Au etchant and Cretchant, and then the resist was stripped so as to form a pair ofpattern electrodes 124, each having a desired comb shaped electrodeportion 124 a. Then, the resultant elements were diced into chipelements so as to obtain the film evaluation elements 121 used forevaluating a B constant and for testing heat resistance.

In addition, the film evaluation elements 121 according to ComparativeExamples, each having the composition ratio of M_(x)Al_(y)(N,O)_(z)(where “M” represents at least one of Fe, Co, Mn, Cu, and Ni) outsidethe range of the present invention and a different crystal system, weresimilarly produced for comparative evaluation.

<Film Evaluation>

(1) Composition Analysis

Elemental analysis was performed by X-ray photoelectron spectroscopy(XPS) on the thin film thermistor portions 3 obtained by the reactivesputtering method. In the XPS, a quantitative analysis was performed ona sputtering surface at a depth of 20 nm from the outermost surface byAr sputtering. The results are shown in Tables 1 to 5. In the followingtables, the composition ratios are expressed by “at %”. Some of thesamples were also subject to a quantitative analysis on a sputteringsurface at a depth of 100 nm from the outermost surface to confirm thatit had the same composition within the quantitative accuracy as that ofthe sputtering surface at a depth of 20 nm.

In the X-ray photoelectron spectroscopy (XPS), a quantitative analysiswas performed under the conditions of an X-ray source of MgKα (350 W), apath energy of 58.5 eV, a measurement interval of 0.125 eV, aphoto-electron take-off angle with respect to a sample surface of 45deg, and an analysis area of about 800 μmφ. Note that the quantitativeaccuracy of N/(M+Al+N+O) and O/(M+Al+N+O) was ±2%, and that of Al/(M+Al)was ±1% (where “M” represents at least one of Fe, Co, Mn, Cu, and Ni).

(2) Specific Resistance Measurement

The specific resistance of each of the thin film thermistor portions 3obtained by the reactive sputtering method was measured by thefour-probe method at a temperature of 25° C. The results are shown inTables 1 to 5.

(3) Measurement of B Constant

The resistance values for each of the film evaluation elements 121 attemperatures of 25° C. and 50° C. were measured in a constanttemperature bath, and a B constant was calculated based on theresistance values at temperatures of 25° C. and 50° C. The results areshown in Tables 1 to 5. In addition, it was confirmed that the filmevaluation elements 121 were thermistors having a negative temperaturecharacteristic based on the resistance values at temperatures of 25° C.and 50° C.

In the present invention, a B constant is calculated by the followingformula using the resistance values at temperatures of 25° C. and 50° C.

B constant (K)=ln(R25/R50)/(1/T25-1/T50)

R25 (Ω): resistance value at 25° C.

R50 (Ω): resistance value at 50° C.

T25 (K): 298.15 K, which is an absolute temperature of 25° C. expressedin Kelvin

T50 (K): 323.15 K, which is an absolute temperature of 50° C. expressedin Kelvin

As can be seen from these results, thermistor characteristics includinga resistivity of 70 Ωcm or higher and a B constant of 1100 K or higherare achieved in all of the Examples in which the composition ratios ofM_(x)Al_(y)(N,O)_(z) (where “M” represents at least one of Fe, Co, Mn,Cu, and Ni) fall within the region enclosed by the points A, B, C, and Din the ternary phase diagrams shown in FIGS. 1 to 5, i.e., the regionwhere “0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55, 0<w≤0.35, and x+y+z=1”.

FIGS. 9 to 13 are graphs illustrating the relationship between aresistivity at 25° C. and a B constant based on the above results. FIG.14 is a graph illustrating the relationship between an Al/(Fe+Al) ratioand a B constant. FIG. 15 is a graph illustrating the relationshipbetween an Al/(Co+Al) ratio and a B constant. FIG. 16 is a graphillustrating the relationship between an Al/(Mn+Al) ratio and a Bconstant. FIG. 17 is a graph illustrating the relationship between anAl/(Cu+Al) ratio and a B constant. FIG. 18 is a graph illustrating therelationship between an Al/(Ni+Al) ratio and a B constant.

These graphs show that the materials, the composition ratios of whichfall within the region where Al/(Fe+Al) is from 0.7 to 0.98 and(N+O)/(Fe+Al+N+O) is from 0.45 to 0.55 and each crystal system of whichis a hexagonal wurtzite-type single phase, have a specific resistancevalue at a temperature of 25° C. of 70 Ωcm or higher and a B constant of1100 K or higher, which is the region realizing a high resistance and ahigh B constant.

These graphs also show that the materials, the composition ratios ofwhich fall within the region where Al/(Co+Al) is from 0.7 to 0.98 and(N+O)/(Co+Al+N+O) is from 0.45 to 0.55 and each crystal system of whichis a hexagonal wurtzite-type single phase, have a specific resistancevalue at a temperature of 25° C. of 70 Ωcm or higher and a B constant of1100 K or higher, which is the region realizing a high resistance and ahigh B constant.

These graphs also show that the materials, the composition ratios ofwhich fall within the region where Al/(Mn+Al) is from 0.7 to 0.98 and(N+O)/(Mn+Al+N+O) is from 0.45 to 0.55 and each crystal system of whichis a hexagonal wurtzite-type single phase, have a specific resistancevalue at a temperature of 25° C. of 70 Ωcm or higher and a B constant of1100 K or higher, which is the region realizing a high resistance and ahigh B constant.

These graphs also show that the materials, the composition ratios ofwhich fall within the region where Al/(Cu+Al) is from 0.7 to 0.98 and(N+O)/(Cu+Al+N+O) is from 0.45 to 0.55 and each crystal system of whichis a hexagonal wurtzite-type single phase, have a specific resistancevalue at a temperature of 25° C. of 70 Ωcm or higher and a B constant of1100 K or higher, which is the region realizing a high resistance and ahigh B constant.

These graphs also show that the materials, the composition ratios ofwhich fall within the region where Al/(Ni+Al) is from 0.7 to 0.98 and(N+O)/(Ni+Al+N+O) is from 0.45 to 0.55 and each crystal system of whichis a hexagonal wurtzite-type single phase, have a specific resistancevalue at a temperature of 25° C. of 70 Ωcm or higher and a B constant of1100 K or higher, which is the region realizing a high resistance and ahigh B constant.

In data shown in FIGS. 14 to 18, the reason why the B constant varieswith respect to the same Al/(Fe+Al), Al/(Co+Al), Al/(Mn+Al), Al/(Cu+Al),or Al/(Ni+Al) ratio is because the materials have different amounts ofnitrogen and/or oxygen in their crystals or different amounts of latticedefects such as nitrogen and/or oxygen defects.

In the materials according to Comparative Examples 2 and 3, where “M” isFe, shown in Table 1, the composition ratios fall within the regionwhere Al/(Fe+Al)<0.7, and the crystal systems are a cubic NaCl-type.Thus, a material with the composition ratio that fall within the regionwhere Al/(Fe+Al)<0.7 have a specific resistance value at a temperatureof 25° C. of less than 70 Ωcm and a B constant of less than 1100 K,which is the region of low resistance and low B constant.

The material according to Comparative Example 1 shown in Table 1 has acomposition ratio that falls within the region where (N+O)/(Fe+Al+N+O)is less than 40% and is in a crystal state where nitridation of metalscontained therein is insufficient. The material according to ComparativeExample 1 was neither a NaCl-type nor wurtzite-type and had very poorcrystallinity. In addition, it was found that the material according tothis Comparative Example exhibited near-metallic behavior because boththe B constant and the resistance value were very small.

In the material according to Comparative Example 2, where “M” is Co,shown in Table 2, the composition ratio falls within the region whereAl/(Co+Al)<0.7, and the crystal system is a cubic NaCl-type. Thus, amaterial with the composition ratio that falls within the region whereAl/(Co+Al)<0.7 has a specific resistance value at a temperature of 25°C. of less than 70 Ωcm and a B constant of less than 1100 K, which isthe region of low resistance and low B constant.

The material according to Comparative Example 1 shown in Table 2 has acomposition ratio that falls within the region where (N+O)/(Co+Al+N+O)is less than 40% and is in a crystal state where nitridation of metalscontained therein is insufficient. The material according to ComparativeExample 1 was neither a NaCl-type nor wurtzite-type and had very poorcrystallinity. In addition, it was found that the material according tothis Comparative Example exhibited near-metallic behavior because boththe B constant and the resistance value were very small.

In the material according to Comparative Example 2, where “M” is Mn,shown in Table 3, the composition ratio falls within the region whereAl/(Mn+Al)<0.7, and the crystal system is a cubic NaCl-type. Thus, amaterial with the composition ratio that falls within the region whereAl/(Mn+Al)<0.7 has a specific resistance value at a temperature of 25°C. of less than 70 Ωcm and a B constant of less than 1100 K, which isthe region of low resistance and low B constant.

The material according to Comparative Example 1 shown in Table 3 has acomposition ratio that falls within the region where (N+O)/(Mn+Al+N+O)is less than 40% and is in a crystal state where nitridation of metalscontained therein is insufficient. The material according to ComparativeExample 1 was neither a NaCl-type nor wurtzite-type and had very poorcrystallinity. In addition, it was found that the material according tothis Comparative Example exhibited near-metallic behavior because boththe B constant and the resistance value were very small.

In the material according to Comparative Example 2, where “M” is Cu,shown in Table 4, the composition ratio falls within the region whereAl/(Cu+Al)<0.7, and the crystal system is a cubic NaCl-type. Thus, amaterial with the composition ratio that falls within the region whereAl/(Cu+Al)<0.7 has a specific resistance value at a temperature of 25°C. of less than 70 Ωcm and a B constant of less than 1100 K, which isthe region of low resistance and low B constant.

The material according to Comparative Example 1 shown in Table 4 has acomposition ratio that falls within the region where (N+O)/(Cu+Al+N+O)is less than 40% and is in a crystal state where nitridation of metalscontained therein is insufficient. The material according to ComparativeExample 1 was neither a NaCl-type nor wurtzite-type and had very poorcrystallinity. In addition, it was found that the material according tothis Comparative Example exhibited near-metallic behavior because boththe B constant and the resistance value were very small.

In the material according to Comparative Example 2, where “M” is Ni,shown in Table 5, the composition ratio fall within the region whereAl/(Ni+Al)<0.7, and the crystal system is a cubic NaCl-type. Thus, amaterial with the composition ratio that falls within the region whereAl/(Ni+Al)<0.7 has a specific resistance value at a temperature of 25°C. of less than 70 Ωcm and a B constant of less than 1100 K, which isthe region of low resistance and low B constant.

The material according to Comparative Example 1 shown in Table 5 has acomposition ratio that falls within the region where (N+O)/(Ni+Al+N+O)is less than 40% and is in a crystal state where nitridation of metalscontained therein is insufficient. The material according to ComparativeExample 1 was neither a NaCl-type nor wurtzite-type and had very poorcrystallinity. In addition, it was found that the material according tothis Comparative Example exhibited near-metallic behavior because boththe B constant and the resistance value were very small.

(4) Thin Film X-Ray Diffraction (Identification of Crystal Phase)

The crystal phases of the thin film thermistor portions 3 obtained bythe reactive sputtering method were identified by Grazing IncidenceX-ray Diffraction. The thin film X-ray diffraction is a small angleX-ray diffraction experiment. The measurement was performed under theconditions of Cu X-ray tube, an angle of incidence of 1 degree, and 20of from 20 to 130 degrees. Some of the samples were measured under thecondition of an angle of incidence of 0 degree and 20 of from 20 to 100degrees.

As a result of the measurement, a wurtzite-type phase (hexagonalcrystal, the same phase as that of AlN) was obtained in the region whereAl/(M+Al)≥0.7 (where “M” represents at least one of Fe, Co, Mn, Cu, andNi), whereas a NaCl-type phase (cubic crystal, the same phase as thoseof FeN, CoN, MnN, CuN, and NiN) was obtained in the region whereAl/(M+Al)<0.65. In addition, it is considered that two coexistingcrystal phases of a wurtzite-type phase and a NaCl-type phase will beobtained in the region where 0.65<Al/(M+Al)<0.7.

Thus, in the M_(x)Al_(y)(N,O)_(z)-based material (where “M” representsat least one of Fe, Co, Mn, Cu, and Ni), the region of high resistanceand high B constant can be realized by the wurtzite-type phase whereAl/(M+Al)≥0.7. In the materials according to Examples of the presentinvention, no impurity phase was confirmed and the crystal structurethereof was a wurtzite-type single phase.

In the materials according to Comparative Examples 1 shown in Tables 1to 5, the crystal phases thereof were neither a wurtzite-type norNaCl-type as described above, and thus, could not be identified in thetesting. In these Comparative Examples, the peak width of XRD was verylarge, showing that the materials had very poor crystallinity. It isconsidered that the crystal phases thereof were metal phases withinsufficient nitridation because they exhibited near-metallic behaviorfrom the viewpoint of electric properties.

TABLE 1 CRYSTAL AXIS EXHIBITING STRONG XRD PEAK DEGREE OF ORIENTATIONINTENSITY IN VERTICAL DIRECTION COMPOSITION RATIO RATIO OF WITH RESPECTTO Fe/ Al/ N/ O/ (100)/(002) SUBSTRATE SURFACE SPUTTER- (Fe + (Fe +(Fe + (Fe + WHEN CRYSTAL WHEN CRYSTAL PHASE ING GAS Al + Al + Al + Al +CRYSTAL PHASE IS IS WURTZITE TYPE PRESSURE N + O) N + O) N − O) N + O)SYSTEM WURTZITE TYPE (a-AXIS OR c-AXIS) (Pa) (%) (%) (%) (%) COMPARATIVEUNKNOWN — — — 9 58 31 2 EXAMPLE 1 (INSUFFICIENT NITRIDATION) COMPARATIVENaCl TYPE — — — 49 2 43 6 EXAMPLE 2 COMPARATIVE NaCl TYPE — — — 22 33 378 EXAMPLE 3 EXAMPLE 1 WURTZITE TYPE 0.20 c-AXIS <1.5 12 35 39 14 EXAMPLE2 WURTZITE TYPE 0.56 c-AXIS <1.5 12 40 41 7 EXAMPLE 3 WURTZITE TYPE 0.29c-AXIS <1.5 7 45 40 8 EXAMPLE 4 WURTZITE TYPE 0.01 c-AXIS <1.5 6 42 47 5EXAMPLE 5 WURTZITE TYPE 0.02 c-AXIS <1.5 4 47 40 9 EXAMPLE 6 WURTZITETYPE 0.02 c-AXIS <1.5 4 47 41 8 EXAMPLE 7 WURTZITE TYPE 0.03 c-AXIS <1.54 43 40 13 EXAMPLE 8 WURTZITE TYPE 0.06 c-AXIS <1.5 4 47 39 10 EXAMPLE 9WURTZITE TYPE 0.38 c-AXIS <1.5 4 49 38 9 EXAMPLE 10 WURTZITE TYPE 0.29c-AXIS <1.5 3 49 42 6 EXAMPLE 11 WURTZITE TYPE 0.26 c-AXIS <1.5 3 48 436 COMPOSITION RATIO (N + O)/ N/ RESULT OF ELECTRIC PROPERTIES Al/ (Fe +Al + (Fe + O/ SPECIFIC RESISTANCE (Fe + Al) N + O) Al + N) (N + O) BCONSTANT VALUE AT 25° C. (%) (%) (%) (%) (K) (Ωcm) COMPARATIVE 87 33 — —8 9.E+00 EXAMPLE 1 COMPARATIVE 4 49 — — 143 1.E+01 EXAMPLE 2 COMPARATIVE61 45 — — 401 4.E+01 EXAMPLE 3 EXAMPLE 1 75 53 45 26 2111 1.E+04 EXAMPLE2 77 48 44 15 1795 3.E+02 EXAMPLE 3 87 48 44 16 1839 6.E+02 EXAMPLE 4 8752 49 9 3992 2.E+06 EXAMPLE 5 92 49 44 18 2738 1.E+05 EXAMPLE 6 92 49 4515 2670 9.E+04 EXAMPLE 7 92 53 46 25 4005 3.E+07 EXAMPLE 8 93 49 44 202872 9.E+04 EXAMPLE 9 93 47 42 19 2158 3.E+04 EXAMPLE 10 94 49 45 132935 7.E+04 EXAMPLE 11 94 49 46 12 2113 3.E+04

TABLE 2 CRYSTAL AXIS EXHIBITING STRONG XRD PEAK DEGREE OF ORIENTATIONINTENSITY IN VERTICAL DIRECTION COMPOSITION RATIO RATIO OF WITH RESPECTTO Co/ Al/ N/ O/ (100)/(002) SUBSTRATE SURFACE SPUTTER- (Co + (Co +(Co + (Co + WHEN CRYSTAL WHEN CRYSTAL PHASE ING GAS Al + Al + Al + Al +CRYSTAL PHASE IS IS WURTZITE TYPE PRESSURE N + O) N + O) N + O) N + O)SYSTEM WURTZITE TYPE (a-AXIS OR c-AXIS) (Pa) (%) (%) (%) (%) COMPARATIVEUNKNOWN — — — 10 61 21 8 EXAMPLE 1 (INSUFFICIENT NITRATATION)COMPARATIVE NaCl TYPE — — — 21 32 40 7 EXAMPLE 2 EXAMPLE 1 WURTZITE TYPE0.26 c-AXIS <1.5 13 36 40 11 EXAMPLE 2 WURTZITE TYPE 0.66 c-AXIS <1.5 1440 37 9 EXAMPLE 3 WURTZITE TYPE 0.02 c-AXIS <1.5 5 43 44 8 EXAMPLE 4WURTZITE TYPE 0.03 c-AXIS <1.5 6 47 42 5 EXAMPLE 5 WURTZITE TYPE 0.13c-AXIS <1.5 6 42 35 17 EXAMPLE 6 WURTZITE TYPE 0.26 c-AXIS <1.5 7 44 409 EXAMPLE 7 WURTZITE TYPE 0.24 c-AXIS <1.5 3 47 43 7 EXAMPLE 8 WURTZITETYPE 0.56 c-AXIS <1.5 3 46 35 16 EXAMPLE 9 WURTZITE TYPE 0.09 c-AXIS<1.5 3 47 43 7 EXAMPLE 10 WURTZITE TYPE 0.02 c-AXIS <1.5 5 46 42 7COMPOSITION RATIO (N + O)/ N/ RESULT OF ELECTRIC PROPERTIES Al/ (Co +Al + (Co + O/ B SPECIFIC RESISTANCE (Co + Al) N + O) Al + N) (N + O)CONSTANT VALUE AT 25° C. (%) (%) (%) (%) (K) (Ωcm) COMPARATIVE 85 28 — —14 9.E+00 EXAMPLE 1 COMPARATIVE 61 47 — — 35 6.E+00 EXAMPLE 2 EXAMPLE 174 51 45 22 1591 7.E+03 EXAMPLE 2 74 46 41 20 1190 9.E+01 EXAMPLE 3 8951 47 15 2085 2.E+03 EXAMPLE 4 89 47 44 10 1932 2.E+04 EXAMPLE 5 88 5242 34 1577 5.E+02 EXAMPLE 6 86 48 44 18 1228 7.E+03 EXAMPLE 7 95 50 4714 3620 3.E+04 EXAMPLE 8 95 52 42 32 2747 3.E+05 EXAMPLE 9 94 50 46 152319 3.E+03 EXAMPLE 10 91 50 46 15 2231 1.E+04

TABLE 3 CRYSTAL AXIS EXHIBITING STRONG XRD PEAK DEGREE OF ORIENTATIONINTENSITY IN VERTICAL DIRECTION COMPOSITION RATIO RATIO OF WITH RESPECTTO Mn/ Al/ N/ O/ (100)/(002) SUBSTRATE SURFACE SPUTTER- (Mn + (Mn +(Mn + (Mn + WHEN CRYSTAL WHEN CRYSTAL PHASE ING GAS Al + Al + Al + Al +CRYSTAL PHASE IS IS WURTZITE TYPE PRESSURE N + O) N + O) N + O) N + O)SYSTEM WURTZITE TYPE (a-AXIS OR c-AXIS) (Pa) (%) (%) (%) (%) COMPARATIVEUNKNOWN — — — 5 70 14 11 EXAMPLE 1 (INSUFFECIENT NITRIDATION)COMPARATIVE NaCl TYPE — — — 21 31 39 9 EXAMPLE 2 EXAMPLE 1 WURTZITE TYPE0.15 c-AXIS <1.5 2 48 45 5 EXAMPLE 2 WURTZITE TYPE 0.36 c-AXIS <1.5 1 4536 18 EXAMPLE 3 WURTZITE TYPE 0.31 c-AXIS <1.5 2 47 41 10 EXAMPLE 4WURTZITE TYPE 0.01 c-AXIS <1.5 3 47 45 5 EXAMPLE 5 WURTZITE TYPE 0.03c-AXIS <1.5 3 49 46 2 EXAMPLE 6 WURTZITE TYPE 0.08 c-AXIS <1.5 7 43 47 3EXAMPLE 7 WURTZITE TYPE 0.06 c-AXIS <1.5 6 43 44 7 EXAMPLE 8 WURTZITETYPE 0.21 c-AXIS <1.5 12 36 42 10 EXAMPLE 9 WURTZITE TYPE 0.46 c-AXIS<1.5 13 39 44 4 COMPOSITION RATIO (N + O)/ N/ RESULT OF ELECTRICPROPERTIES Al/ (Mn + Al + (Mn + O/ B SPECIFIC RESISTANCE (Mn + Al) N +O) Al + N) (N + O) CONSTANT VALUE AT 25° C. (%) (%) (%) (%) (K) (Ωcm)COMPARATIVE 94 25 — — 66 2.E−03 EXAMPLE 1 COMPARATIVE 60 48 — — 2669.E−02 EXAMPLE 2 EXAMPLE 1 96 50 47 10 3052 2.E+05 EXAMPLE 2 97 53 43 335115 6.E+05 EXAMPLE 3 97 52 46 20 5728 4.E+05 EXAMPLE 4 95 50 47 10 29805.E+03 EXAMPLE 5 94 48 47 3 2865 4.E+03 EXAMPLE 6 86 50 49 5 2671 2.E+04EXAMPLE 7 87 51 47 13 2488 2.E+03 EXAMPLE 8 75 52 47 18 2215 3.E+03EXAMPLE 9 75 48 46 9 1788 2.E+02

TABLE 4 CRYSTAL AXIS EXHIBITING STRONG XRD PEAK DEGREE OF ORIENTATIONINTENSITY IN VERTICAL DIRECTION COMPOSITION RATIO RATIO OF WITH RESPECTTO Cu/ Al/ N/ O/ (100)/(002) SUBSTRATE SURFACE SPUTTER- (Cu + (Cu +(Cu + (Cu + WHEN CRYSTAL WHEN CRYSTAL PHASE ING GAS Al + Al + Al + Al +CRYSTAL PHASE IS IS WURTZITE TYPE PRESSURE N + O) N + O) N + O) N + O)SYSTEM WURTZITE TYPE (a-AXIS OR c-AXIS) (Pa) (%) (%) (%) (%) COMPARATIVEUNKNOWN — — — 11 63 21 5 EXAMPLE 1 (INSUFFECIENT NITRIDATION)COMPARATIVE NaCl TYPE — — — 23 30 41 6 EXAMPLE 2 EXAMPLE 1 WURTZITE TYPE0.04 c-AXIS <1.5 13 40 44 3 EXAMPLE 2 WURTZITE TYPE 0.06 c-AXIS <1.5 1335 37 15 EXAMPLE 3 WURTZITE TYPE 0.12 c-AXIS <1.5 5 44 49 2 EXAMPLE 4WURTZITE TYPE 0.04 c-AXIS <1.5 6 46 42 6 EXAMPLE 5 WURTZITE TYPE 0.05c-AXIS <1.5 3 47 48 2 EXAMPLE 6 WURTZITE TYPE 0.08 c-AXIS <1.5 3 45 3616 EXAMPLE 7 WURTZITE TYPE 0.25 c-AXIS <1.5 4 47 43 6 COMPOSITION RATIO(N + O)/ N/ RESULT OF ELECTRIC PROPERTIES Al/ (Cu + Al + (Cu + O/ BSPECIFIC RESISTANCE (Cu + Al) N + O) Al + N) (N + O) CONSTANT VALUE AT25° C. (%) (%) (%) (%) (K) (Ωcm) COMPARATIVE 85 26 — — 14 1.E−03 EXAMPLE1 COMPARATIVE 57 48 — — 44 3.E−02 EXAMPLE 2 EXAMPLE 1 75 48 46 7 14011.E+03 EXAMPLE 2 73 52 43 29 1303 2.E+02 EXAMPLE 3 89 50 50 3 19942.E+03 EXAMPLE 4 88 48 44 13 1836 3.E+03 EXAMPLE 5 94 50 49 4 28655.E+05 EXAMPLE 6 94 52 43 31 2689 2.E+05 EXAMPLE 7 93 49 46 13 21891.E+04

TABLE 5 CRYSTAL AXIS EXHIBITING STRONG XRD PEAK DEGREE OF ORIENTATIONINTENSITY IN VERTICAL DIRECTION COMPOSITION RATIO RATIO OF WITH RESPECTTO Ni/ Al/ N/ O/ (100)/(002) SUBSTRATE SURFACE SPUTTER- (Ni + (Ni +(Ni + (Ni + WHEN CRYSTAL WHEN CRYSTAL PHASE ING GAS Al + Al + Al + Al +CRYSTAL PHASE IS IS WURTZITE TYPE PRESSURE N + O) N + O) N + O) N + O)SYSTEM WURTZITE TYPE (a-AXIS OR c-AXIS) (Pa) (%) (%) (%) (%) COMPARATIVEUNKNOWN — — — 5 79 11 5 EXAMPLE 1 (INSUFFICIENT NITRIDATION) COMPARATIVENaCl TYPE — — — 21 32 41 6 EXAMPLE 2 EXAMPLE 1 WURTZITE TYPE 0.04 c-AXIS<1.5 13 36 40 11 EXAMPLE 2 WURTZITE TYPE 0.06 c-AXIS <1.5 13 39 45 3EXAMPLE 3 WURTZITE TYPE 0.12 c-AXIS <1.5 4 48 44 4 EXAMPLE 4 WURTZITETYPE 0.04 c-AXIS <1.5 3 46 37 14 EXAMPLE 5 WURTZITE TYPE 0.03 c-AXIS<1.5 6 43 49 2 COMPOSITION RATIO (N + O)/ N/ RESULT OF ELECTRICPROPERTIES Al/ (Ni + Al + (Ni + O/ B SPECIFIC RESISTANCE (Ni + Al) N +O) Al + N) (N + O) CONSTANT VALUE AT 25° C. (%) (%) (%) (%) (K) (Ωcm)COMPARATIVE 94 16 — — 16 1.E−03 EXAMPLE 1 COMPARATIVE 60 47 — — 433.E−02 EXAMPLE 2 EXAMPLE 1 74 51 45 21 1286 3.E+02 EXAMPLE 2 75 49 47 71505 1.E+03 EXAMPLE 3 93 48 46 8 2761 4.E+05 EXAMPLE 4 94 51 43 28 24892.E+05 EXAMPLE 5 87 50 50 3 1966 2.E+03

Next, since all the materials according to the Examples of the presentinvention were wurtzite-type phase films having strong orientation,whether the films have a strong a-axis orientation or c-axis orientationin the crystal extending in a vertical direction (film thicknessdirection) with respect to the Si substrate (S) was examined by XRD. Atthis time, in order to examine the orientation of the crystal axis, thepeak intensity ratio of (100)/(002) was measured, where (100) is the hklindex indicating a-axis orientation and (002) is the hkl indexindicating c-axis orientation.

As a result of the measurement, in all the Examples of the presentinvention, the intensity of (002) was much stronger than that of (100),that is, the films exhibited a stronger c-axis orientation than a-axisorientation.

Note that it was confirmed that a wurtzite-type single phase was formedin the same manner even when the thin film thermistor portion 3 wasdeposited on a polyimide film under the same deposition condition. Itwas also confirmed that the crystal orientation did not change even whenthe thin film thermistor portion 3 was deposited on a polyimide filmunder the same deposition condition.

FIGS. 19 to 23 show exemplary XRD profiles of materials according toExamples of the present invention. In the Example shown in FIG. 19,Al/(Fe+Al) was equal to 0.92 (wurtzite-type, hexagonal crystal), and themeasurement was performed at a 1 degree angle of incidence. In theExample shown in FIG. 20, Al/(Co+Al) was equal to 0.89 (wurtzite-type,hexagonal crystal), and the measurement was performed at a 1 degreeangle of incidence. In the Example shown in FIG. 21, Al/(Mn+Al) wasequal to 0.95 (wurtzite-type, hexagonal crystal), and the measurementwas performed at a 1 degree angle of incidence. In the Example shown inFIG. 22, Al/(Cu+Al) was equal to 0.89 (wurtzite-type, hexagonalcrystal), and the measurement was performed at a 1 degree angle ofincidence. In the Example shown in FIG. 23, Al/(Ni+Al) was equal to 0.75(wurtzite-type, hexagonal crystal), and the measurement was performed ata 1 degree angle of incidence.

As can be seen from these results, the intensity of (002) was muchstronger than that of (100) in these Examples.

The asterisk (*) in the graphs shows the peak originating from thedevice or the Si substrate with a thermal oxidation film, and thus, itwas confirmed that the peak with the asterisk (*) in the graphs wasneither the peak originating from a sample itself nor the peakoriginating from an impurity phase. In addition, a symmetricalmeasurement was performed at a 0 degree angle of incidence, confirmingthat the peak indicated by (*) was lost in the symmetrical measurement,and thus, that it was the peak originating from the device or the Sisubstrate with a thermal oxidation film.

The wurtzite-type materials according to Examples of the presentinvention were further examined for the correlation between the amountsof nitrogen and oxygen. FIG. 24 shows the examination result of therelationship between an N/(Fe+Al+N) ratio and an O/(N+O) ratio. As canbe seen from this result, a sample having a lower N/(Fe+Al+N) ratio hasa higher O/(N+O) ratio.

<Crystalline Form Evaluation>

FIG. 29 shows a cross-sectional SEM photograph of the thin filmthermistor portion 3 according to an Example where “M” is Fe (whereAl/(Fe+Al)=0.92, wurtzite-type, hexagonal crystal, and strong c-axisorientation), in which the thin film thermistor portion 3 having athickness of about 450 nm was deposited on the Si substrate (S) with athermal oxidation film, as an exemplary crystalline form in thecross-section of the thin film thermistor portion 3.

FIG. 30 shows a cross-sectional SEM photograph of the thin filmthermistor portion 3 according to an Example where “M” is Co (whereAl/(Co+Al)=0.89, wurtzite-type, hexagonal crystal, and strong c-axisorientation), in which the thin film thermistor portion 3 having athickness of about 450 nm was deposited on the Si substrate (S) with athermal oxidation film.

FIG. 31 shows a cross-sectional SEM photograph of the thin filmthermistor portion 3 according to an Example where “M” is Mn (whereAl/(Mn+Al)=0.95, wurtzite-type, hexagonal crystal, and strong c-axisorientation), in which the thin film thermistor portion 3 having athickness of about 180 nm was deposited on the Si substrate (S) with athermal oxidation film.

FIG. 32 shows a cross-sectional SEM photograph of the thin filmthermistor portion 3 according to an Example where “M” is Cu (whereAl/(Cu+Al)=0.94, wurtzite-type, hexagonal crystal, and strong c-axisorientation), in which the thin film thermistor portion 3 having athickness of about 480 nm was deposited on the Si substrate (S) with athermal oxidation film.

FIG. 33 shows a cross-sectional SEM photograph of the thin filmthermistor portion 3 according to an Example where “M” is Ni (whereAl/(Ni+Al)=0.93, wurtzite-type, hexagonal crystal, and strong c-axisorientation), in which the thin film thermistor portion 3 having athickness of about 300 nm was deposited on the Si substrate (S) with athermal oxidation film.

The samples in these Examples were obtained by breaking the Sisubstrates (S) by cleavage. The photographs were taken by tiltobservation at an angle of 45 degrees.

As can be seen from these photographs, the samples were formed ofhigh-density columnar crystals in all Examples of the present invention.Specifically, the growth of columnar crystals in a vertical directionwith respect to the surface of the substrate was observed. Note that thebreak of the columnar crystal was generated upon breaking the Sisubstrate (S) by cleavage.

The columnar crystal size of the sample according to the Example in FIG.29, where “M” is Fe, was about 15 nmφ (±5 nmφ) in grain size, and about310 nm in length. The columnar crystal size of the sample according tothe Example in FIG. 30, where “M” is Co, was about 15 nmφ (±10 nmφ) ingrain size, and about 340 nm in length. The columnar crystal size of thesample according to the Example in FIG. 31, where “M” is Mn, was about12 nmφ(±5 nmφ) in grain size, and about 180 nm in length. The columnarcrystal size of the sample according to the Example in FIG. 32, where“M” is Cu, was about 20 nmφ(±10 nmφ) in grain size, and about 480 nm inlength. The columnar crystal size of the sample according to the Examplein FIG. 33, where “M” is Ni, was about 20 nmφ(±10 nmφ) in grain size,and about 300 nm (±50 nm) in length.

The grain size here is the diameter of a columnar crystal along thesurface of a substrate, and the length is that of a columnar crystal ina vertical direction with respect to the surface of the substrate (filmthickness).

When the aspect ratio of a columnar crystal is defined as “length/grainsize”, the materials according to the present Examples have an aspectratio of 10 or higher. It is contemplated that the films have a highdensity due to the small grain size of a columnar crystal.

It was also confirmed that when a film having a thickness of 200 nm, 500nm, or 1000 nm was deposited on the Si substrate (S) with a thermaloxidation film, high-density columnar crystals were formed as describedabove.

<Heat Resistance Test Evaluation>

For the thin film thermistor portions 3 according to some of theExamples and the Comparative Examples shown in Tables 1 to 5, aresistance value and a B constant before and after the heat resistancetest at a temperature of 125° C. for 1000 hours in air were evaluated.The results are shown in Tables 6 to 10. The thin film thermistorportion 3 according to the Comparative Example made of a conventionalTa—Al—N-based material was also evaluated in the same manner forcomparison. In addition, for reference, the thin film thermistor portion3 according to Reference Example 1 made of an M-Al—N based material(where “M” represents at least one of Fe, Co, Mn, Cu, and Ni)(wurtzite-type, hexagonal crystal, strong c-axis orientation), which wasformed by performing reactive sputtering under a mixed gas (nitrogengas+Ar gas) atmosphere containing no oxygen gas, was similarly subjectto the heat resistance test. The results are also shown in Tables 6 to10.

As can be seen from these results, although the Al concentration and thenitrogen concentration vary, both the rising rate of a resistance valueand the rising rate of a B constant of the M_(x)Al_(y)(N,O)_(z)materials (where “M” represents at least one of Fe, Co, Mn, Cu, and Ni)according to the Examples are smaller, and the heat resistance thereofbased on the change of electric properties before and after the heatresistance test is more excellent as compared with the Ta—Al—N-basedmaterial according to the Comparative Example when both materials havealmost the same B constant.

In addition, it can be found that although the heat resistance of theM-Al—N-based material (where “M” represents at least one of Fe, Co, Mn,Cu, and Ni) according to Reference Example 1, which does not positivelycontain oxygen, is more excellent than that of the Comparative Example,the M-Al—N—O-based materials (where “M” represents at least one of Fe,Co, Mn, Cu, and Ni) according to the Examples of the present invention,which positively contain oxygen, have a lower rising rate of resistancevalue and more excellent heat resistance as compared with ReferenceExample 1.

Note that, in the Ta—Al—N-based material, the ionic radius of Ta is verylarge compared to that of Fe, Co, Mn, Cu, Ni, and Al, and thus, awurtzite-type phase cannot be produced in the high-concentration Alregion. It is contemplated that the M-Al—N-based material (where “M”represents at least one of Fe, Co, Mn, Cu, and Ni) or the M-Al—N—O-basedmaterial (where “M” represents at least one of Fe, Co, Mn, Cu, and Ni)having a wurtzite-type phase has a better heat resistance than theTa—Al—N-based material because the Ta—Al—N-based material does not havea wurtzite-type phase.

TABLE 6 RISING RATE OF SPECIFIC RISING RATE OF SPECIFIC RESISTANCE AT BCONSTANT RESISTANCE 25° C. AFTER AFTER HEAT M Al/ VALUE HEAT RESISTANCERESISTANCE TEST ELE- M Al N O (M + Al) B25-50 AT 25° C. TEST AT 125° C.AT 125° C. FOR MENT (%) (%) (%) (%) (%) (K) (Ωcm) FOR 1,000 HOURS (%)1,000 HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLEEXAMPLE 5 Fe 4 47 40 9 92 2738 1.E+05 <2 <1 EXAMPLE 6 Fe 4 47 41 8 922670 9.E+04 <2 <1 REFERENCE Fe 4 52 44 — 92 2714 4.E+04 <4 <1 EXAMPLE 1

TABLE 7 RISING RATE OF SPECIFIC RISING RATE OF SPECIFIC RESISTANCE AT BCONSTANT RESISTANCE 25° C. AFTER AFTER HEAT M Al/ VALUE AT HEATRESISTANCE RESISTANCE TEST ELE- M Al N O (M + Al) B25-50 25° C. TEST AT125° C. AT 125° C. FOR MENT (%) (%) (%) (%) (%) (K) (Ωcm) FOR 1,000HOURS (%) 1,000 HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6EXAMPLE EXAMPLE 3 Co 5 43 44 8 89 2085 2.E+03 <4 <2 REFERENCE Co 6 47 47— 89 2075 1.E+03 <5 <2 EXAMPLE 1

TABLE 8 RISING RATE OF SPECIFIC RISING RATE OF SPECIFIC RESISTANCE AT BCONSTANT RESISTANCE 25° C. AFTER AFTER HEAT M Al/ VALUE HEAT RESISTANCERESISTANCE TEST ELE- M Al N O (M + Al) B25-50 AT 25° C. TEST AT 125° C.AT 125° C. FOR MENT (%) (%) (%) (%) (%) (K) (Ωcm) FOR 1,000 HOURS (%)1,000 HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLEEXAMPLE 4 Mn 3 47 45 5 95 2980 5.E+03 <4 <2 REFERENCE Mn 3 49 48 — 942863 3.E+03 <5 <2 EXAMPLE 1

TABLE 9 RISING RATE OF SPECIFIC RISING RATE OF SPECIFIC RESISTANCE AT BCONSTANT RESISTINCE 25° C. AFTER AFTER HEAT M Al/ VALUE HEAT RESISTANCERESISTANCE TEST ELE- M Al N O (M + Al) B25-50 AT 25° C. TEST AT 125° C.AT 125° C. FOR MENT (%) (%) (%) (%) (%) (K) (Ωcm) FOR 1,000 HOURS (%)1,000 HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLEEXAMPLE 5 Cu 3 47 48 2 94 2865 5.E+05 <5 <3 REFERENCE Cu 3 48 49 — 942757 4.E+05 <6 <3 EXAMPLE 1

TABLE 10 RISING RATE OF SPECIFIC RISING RATE OF SPECIFIC RESISTANCE AT BCONSTANT RESISTANCE 25° C. AFTER AFTER HEAT M Al/ VALUE AT HEATRESISTANCE RESISTANCE TEST ELE- M Al N O (M + Al) B25-50 25° C. TEST AT125° C. AT 125° C. FOR MENT (%) (%) (%) (%) (%) (K) (Ωcm) FOR 1,000HOURS (%) 1,000 HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6EXAMPLE EXAMPLE 3 Ni 4 48 44 4 93 2761 4.E+05 <5 <3 REFERENCE Ni 5 49 46— 92 2657 2.E+05 <6 <3 EXAMPLE 1

The technical scope of the present invention is not limited to theaforementioned embodiments and Examples, but the present invention maybe modified in various ways without departing from the scope or teachingof the present invention.

REFERENCE NUMERALS

1: film-type thermistor sensor, 2: insulating film, 3: thin filmthermistor portion, 4 and 124: pattern electrode

What is claimed is:
 1. A thermistor made of a metal nitride material,the metal nitride material consisting of a metal nitride represented bythe general formula: M_(x)Al_(y)(N_(1-w)O_(w))_(z) (where “M” representsat least one of Fe, Co, Mn, Cu, and Ni, 0.70≤y/(x+y)≤0.98, 0.45≤z≤0.55,0<w≤0.35, and x+y+z=1), wherein the crystal structure thereof is ahexagonal wurtzite-type single phase.
 2. The thermistor according toclaim 1, wherein the metal nitride material is deposited as a film andis a columnar crystal extending in a vertical direction with respect tothe surface of the film.
 3. A film-type thermistor sensor comprising: aninsulating film; a thin film thermistor portion made of the thermistoraccording to claim 2 formed on the insulating film; and a pair ofpattern electrodes formed at least on the top or the bottom of the thinfilm thermistor portion.
 4. A method for producing the thermistoraccording to claim 2, the method comprising a deposition step ofperforming film deposition by reactive sputtering in a nitrogen andoxygen-containing atmosphere using an M-Al alloy sputtering target(where “M” represents at least one of Fe, Co, Mn, Cu, and Ni).
 5. Afilm-type thermistor sensor comprising: an insulating film; a thin filmthermistor portion made of the thermistor according to claim 1 formed onthe insulating film; and a pair of pattern electrodes formed at least onthe top or the bottom of the thin film thermistor portion.
 6. A methodfor producing the thermistor according to claim 1, the method comprisinga deposition step of performing film deposition by reactive sputteringin a nitrogen and oxygen-containing atmosphere using an M-Al alloysputtering target (where “M” represents at least one of Fe, Co, Mn, Cu,and Ni).